Northern and Southern Caribbean Festoons (Panama, Colombia-Venezuela and Hispa-Niola - Puerto Rico), Interpreted as Pseudosubductions Induced by the East-West Shortening of the Pericaribbean Continental Frame

Abstract

The Caribbean plate is moving eastward, relatively to and between the two Americas, at about 2 cm/year. This motion is expressed : - laterally by large strike-slip movements, sinistral on the North side, dextral on the right one; - at the leading edge, to the East, by the Lesser Antilles subduction zone and the Barbados accretionary prism. The Caribbean plate is made of a central domain with oceanic crust, more or less thickened, surrounded by a continental frame. This frame is deformed and draws arched structures (“festoons”) with a Caribbean convexity : the Panama and the Colombia - Venezuela festoons to the South; the Hispaniola-Puerto-Rico (= Los Muertos) festoon, to the North. These structures orientated at 90° to the Lesser Antilles Arc, geometrically mime subduction zones, with their frontal accretionary prism similar to the Barbados or Nankai one. Nevertheless, they do not have the seismicity nor the volcanism tied to subductions : we propose to call them “pseudosubductions”. These arched structures are classically interpreted by the authors as the result of the light convergence (<1 cm/an) between the North and South American plates. Structural and seismotectonics data allow us to propose a different mechanism. The Caribbean festoons could be the result of the bending of the Caribbean continental frame related to an approximatly E.W. shortening. Due to the geometry of the continental borders (Panama and Hispaniola Puerto-Rico) and/or to the displacement along intra-continental strike slip faults (Colombia - Venezuela, with the northern extrusion of the Maracaibo block between the Bocono and the Santa Marta - Bucaramanga faults), this bending creates the pseudosubductions.